How much Camera sampling AA is too much

[osukas]

I'm using Arnold for render a scene, I'm having a lot of flickering in some small elements, Increased the diffuse or Specular samples doesn't do much, after seeing this: Removing Noise Workflow diagram - Arnold for 3ds Max I noticed in the alpha some elements has missing parts, so Instead of using 3 as Camera AA I did a lot of renders and the one that feels without any flickering is 24 AA, takes a lot of time but the render finally looks smooth. 

I'm trying using now Adaptive Sampling to improve the render time, I put the min at 3 and max at 24. Is a 25% faster

I think that AA 24 might be too high, I want to solve this smartly and not Brute force my way to have better quality (because of longer render times)

I can´t show the image because of NDA, but are some realistic elements to be added on recorded footage.

A coworker told me that the her teacher that worked in studio projects always used all 5 in the sampling, and worked most of the time

Camera (AA):5 - Diffuse: 5 - Specular: 5 - Tranmision: 5... etc etc etc

I used that config in my project and was still super noisy.

If you had experience in projects for studios, normally how much sampling you had to use?

[CiroCardoso3v]

24 is quite a lot. Can you identify where this flickering is? Which AOV shows the noise? From experience, usually when you have high specular values that brings some fireflies. Still, the 5, 5, 5, rule is a little bit too high. On top of that, for more difficult scenes, you may want to check the Arnold Noice to remove the more difficult noise areas.

[lee_griggs]

Can you crop a section of the image so that we can identify the type of noise? Ciro is right, you can use AOVs to identify where the noise is coming from. 5 Camera (AA) samples should be enough unless the noise is from motion blur or heavy DOF. 

https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_3ds_max_ax_removing_noise_ax_identify_nois...

[osukas]

Hi CiroCardoso3v, here is an update on my render

with this I'm getting something decent, I modified some of the problematic materials in the car, for example I had parts with a mirror-like material 100% metallic. I reduced specular to 0.5, and increased the roughness to 0.2, and I clamped some fireflies in the render settings. This helped me to reduce a lot of my problems.

The shadows on the floor looks really nice so I know that isn't the sampling in the lights, I still have some noise/flickering in my video, 

I tried to use Noice but doesn't work on my AOVs, y make a lot of lights AOVS for the composition process.

Also most of my renders has empty spaces (I always render elements to be added in post, so I use a lot of shadow mattes) when I increase the camera AA, the render-core spends more time in areas where is nothing, thats why I use a lot the Adaptive sampling, the problem is if I decrease too much the min AA and increase the MAX samples, I get messy alphas, even when reducing the adaptive Threshold.

I want to get better at Arnold for my renders

[osukas]

@lee_griggs I can´t share a pic because of NDA, and most of the noise is visible when I play the image sequence, with a still image the problem isnt visible. And the Camera is the only object moving in scene, no motion/depth blur because will be added in POST

I followed the guide and most of the flickering comes small elements (small lightbulbs, nets)  and very reflective objects. 

[osukas]

Testing the CameraAA with no lights or shadows, to only see the alpha and look for the right value

AA4 gives me some small noise, and is acceptable. Also I was testing the Adaptive Threshold values and none affect the alpha of the scene, tried different values and none had changes, a 2min to 12max has more noise in the alpha than using a constant 4 in Camera AA

[CiroCardoso3v · Accepted solution]

To denoise the AOVs there is a way and I can send you a direct message explaining it or even here. Let me know if you are interested.

Is this an interior or exterior scene? Exterior scenes should be fairly easy to get clean renders. If it is an interior scene, I found that some extra lights to bounce light, actually help quite a lot to get faster and cleaner renders. But one of the biggest culprits is for sure materials that need to be fixed. Like materials that are 100% reflective, with roughness set to 1, or with pure white or black values.

The example you showed with the camera AA, is exactly what the Camera AA does. Brings more definition to those small details, DOF and motion blur. At the same time, it acts as a multiplier for all the other samples, so if you increase the Camera AA, you can and should decrease the samples for diffuse, specular, etc. When I have small details, I have scenes with 6 or 10 for Camera AA and 1 for everything else.

[osukas]

Hello Ciro, returning today to the render.

Now I set my project with all the values in 0, and only setting the Camera AA with my main lights to make the small details work, and then activate the other stuff. At AA6 is looking a lot better

Finally I understood how the multipliers work, and makes sense your way of having the AA in 6-10 and use 1 on the rest.

Thanks a lot

The Scene is in exterior. Is some vehicles over recorded footage, I'm interested how to denoise the AOVs

[CiroCardoso3v]

Happy to help. Let us know if you have any more questions. As soon as you understand how to use the samples, everything else becomes easy and simple to do.